A standard bath typically is filled generally with warm water, from taps or a mixer and spout, and is used for bathing.
A spa bath also incorporates an intake and a number of spa jets positioned in the bath side walls, and piping around the exterior of the bath, through which water is circulated from an intake to the jets in the side walls of the bath by one or more pumps. A spa bath provides the bather(s) with a more luxuriant bathing experience.
A whirpool available from Kohler Co may include a pillow with one or more associated neck jets that deliver water at the base of a reclining bathers neck (see www.kohlerco.com).